Medical device having a branch and process for producing the same

ABSTRACT

A process for producing a medical device having a branch includes the steps of: welding a bottom of the tubular member on a mounting surface of a constituent material of a main tube extruded under elevated temperature, welding firmly the bottom of the tubular member to the mounting surface of the main tube while aspirating the constituent material of the main tube from above the tubular member, forming a hole in the mounting surface of the main tube so as to communicate an interior of the tubular member with an interior of the main tube, and cutting the main tube, thereby assembling the medical device having the branch.

This is a divisional of application Ser. No. 08/991,211 filed Dec. 16,1997, now U.S. Pat. No. 6,022,441, the disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a medical device having a main tubewhich has a branch (e.g. Y and T tubes) connected to a branchline tube(for injecting medical fluids into the main tube and for monitoring thepressure on the main tube). The invention also relates to a medicaldevice which has a plug fitted into the branch to form processingportions for performing several functions such as injection of medicalfluids into the main tube (in this case, the processing portion is amixing/injecting portion), sampling fluids from within the main tube (afluid sampling portion) and monitoring the pressure in the main tube (apressure monitoring portion), as exemplified by body fluid processingcircuits, administration, blood sampling and blood transfusion sets, aswell as administration, blood sampling and blood transfusion bags whichare to be used either alone or in connection to those sets and circuits.The invention also relates to a process for producing such medicaldevices.

2. Description of the Related Art

The present invention will now be described in detail with particularreference to a body fluid processing circuit including a main tube madeof a synthetic resin and which has branchline tubes and processingportions such as a mixing/injecting portion welded at several sitesalong its length, as well as to a process for producing the circuit.

As is well known, artificial kidneys, artificial lungs, plasmaseparators and other body fluid processors are equipped with body fluidprocessing circuits for connecting these apparatus to the human body.FIG. 36 shows an exemplary arterial blood circuit to be connected to anartificial kidney. As shown, the circuit includes a main tube 101 whichusually has many branches provided along its length and they include aphysiological saline filling line 102, a mixing/injecting portion 103and a heparin line 104. Conventionally, the production of such brancheshas involved very cumbersome steps and required considerable skill.

A section of the mixing/injecting portion 103 is shown in FIG. 37. Theconventional procedure of assembling this portion is shown in FIG. 38and includes cutting the main tube 101 at a suitable site, applying asolvent 105 to the tips of the cut sections of the tube 101, pressingthem into a connecting tube 107 with fingers, subsequently inserting arubber plug 108 such as to close an opening 106 in the connecting tube107 and fitting a cover 109 over the rubber plug 108.

This procedure is entirely manual and hence very cumbersome; inaddition, controlling the coating weight of the solvent is difficult andrequires considerable skill. If the solvent is applied in amore-than-necessary amount, the excess portion will come out of thejoint, protrudes inward of the tube and solidifies to form lumpsindicated by 110 in FIG. 37. The lumps 110 will increase the frictionalresistance of blood flowing through the main tube, causing a turbulencein the blood which should form a laminar flow in a normal smoothconduit. This can be a cause of the disruption of blood components,which in turn may induce blood coagulation.

If the amount of the solvent is unduly small, not only is the main tube101 joined to the connecting tube 107 insufficiently but also theresulting gap may potentially provide a passageway for the leakage ofblood. In addition, the method of joining the two members by solventapplication has a microbial contamination hazard or the solvent maydissolve in the blood to potentially cause adverse effects on the humanbody.

The following disadvantages and defects have been additionally pointedout to exist in the related art: (1) while the main tube 101 is moldedby extrusion, the connecting tube 107 must separately be formed byinjection and due to the different shrinkage ratios of the two moldedparts, they cannot be joined together without producing steps in thejoint; in addition, so many parts have to be assembled that theproduction cost increases and parts control is prone to be a cumbersometask; (2) the bore of the main tube 101 has to be adjusted to the exactdimension which fits to the connecting tube 107 and, in addition, itmust be cut to the specified correct length; this only adds to thenumber of production steps and, hence, the manpower that is required;(3) due to the distortion introduced in the cut surfaces of the maintube 101, the latter will not fit closely to the connecting tube 107 andthe applied solvent will adhere firmly to unwanted areas, therebyforming asperities which in turn cause blood coagulation and othertroubles; (4) post-assembly sterilization will distort the joint betweenthe main tube 101 and the connecting tube 107 and the distorted areasbecome accordingly smaller in diameter or steps may form to therebyupset the blood flow, which can be a cause of blood coagulation,residual blood or hemolysis.

For example, even a step about 0.1 mm (100 μm) high which is difficultto identify with the naked eye is an obstacle at least 10 times as largeas erythrocytes which are the largest (8 μm is diameter) of the bloodcomponents; see FIG. 39 which shows enlarged encircled area A of FIG.37. As a result, erythrocytes in the blood flowing through the main tube101 to enter the connecting tube 107 impinge on the step and cannot moveany farther. The erythrocytes gradually build up in areas around thestep to become a cause of blood coagulation or residual blood and thedisrupted erythrocytes resulting from the impingement will be a cause ofhemolysis.

(5) The opening 106 in the connecting tube 107 is also wide enough topotentially cause the same problem as described in (4), i.e., blood maybuild up in areas about the step of the opening 106 to thereby causeclotting and residual blood.

(6) In the structure shown in FIG. 37 which has the main tube 101connected to the connecting tube 107, the former is typically formed ofa flexible synthetic resin and the latter of a rigid synthetic resin;hence, as shown in FIG. 40, the main tube 101 often kinks at sites nearthe connecting tube 107.

Under the circumstances, Japanese Patent Unexamined Publication No.124249/1995 discloses a body fluid processing circuit having a main tubeformed to have a straight surface without any seams present along itslength, as well as a process for producing the circuit.

However, because of the absence of any holes in the main tube at thesite where the mixing/injecting portion is formed, it is difficult topierce a needle into the main tube. On the other hand, a small hole 121(see FIG. 41) is formed in the mounting surface of the main tube 124;however, as is clear from FIG. 41, the small hole is formed with itsouter peripheral surface protruding inward and when blood or othermedical fluids contacted the protrusion 122, there is the possibilityfor the occurrence of stagnation, clotting, residual blood and othertroubles.

SUMMARY OF THE INVENTION

The present invention has been accomplished on the basis of theintensive studies made by the inventors to eliminate the aforementioneddisadvantages and defects of the prior art and its principal object isto provide a more improved method capable of efficient production ofbranches, such as the mixing injecting portion and the branchline,without the necessity of cutting the main tube and using solvents.

In one aspect, the present invention provides a process for producing amedical device having a branch, which includes the following steps:extruding a tubular form of a constituent material for a first tubeunder elevated temperature; welding a second tube firmly to the mountingsurface of the first tube while aspirating the constituent material ofthe first tube from above the second tube; forming a hole in themounting surface of the first tube by the aspiration such as toestablish communication between the interior of the first tube and theinterior of the second tube; and cutting the main first and assemblingthe medical device having branches.

In another aspect, the present invention provides a medical devicehaving a branch, which includes: a first tube formed to have a straightsurface without any seams present along its length; and a second tubewelded firmly to the mounting surface of the first tube; with a holebeing formed in the mounting surface of the first tube to establishcommunication with the second tube; and the outer peripheral surface ofthe hole being curved toward the mounting surface of the first tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating an embodiment of theinvention for producing a body fluid processing circuit;

FIG. 2 is a partial enlarged view showing the first step of welding atubular member to the main tube in the process shown in FIG. 1;

FIG. 3 is a partial enlarged view of the step subsequent to the stepshown in FIG. 2;

FIG. 4 is a partial enlarged view of the step subsequent to the stepshown in FIG. 3;

FIG. 5 is a schematic diagram illustrating a step in another exemplaryprocess for producing the body fluid processing circuit of theinvention;

FIG. 6 is a schematic diagram showing the step subsequent to the stepshown in FIG. 5;

FIG. 7 is a schematic diagram showing the step subsequent to the stepshown in FIG. 6;

FIG. 8 shows enlarged a tubular member 8a to which a branchline tube 14is connected to provide a flush surface;

FIG. 9 is a schematic diagram showing how a mixing/injecting portion isassembled by pressing a rubber plug into a tubular member 8;

FIG. 10 is section A--A of FIG. 9;

FIG. 11 is a partial enlarged view showing a step in yet anotherexemplary process for producing the body fluid processing circuit of theinvention;

FIG. 12 is a partial enlarged view showing the step subsequent to thestep shown in FIG. 11;

FIG. 13 is a partial enlarged view showing the step subsequent to thestep shown in FIG. 12;

FIG. 14 is a partial enlarged view showing a modification of the stepshown in FIG. 12;

FIG. 15 is a partial enlarged view showing a step in a further exemplarymethod of producing the body fluid processing circuit of the invention;

FIG. 16 is a partial enlarged view showing a step in another exemplarymethod of producing the body fluid processing circuit of the invention;

FIG. 17 is a partial enlarged view showing a modification of the stepshown in FIG. 15;

FIG. 18 is a partial enlarged view showing a modification of the stepshown in FIG. 16;

FIG. 19 is a schematic diagram illustrating another embodiment of theinvention for producing a body fluid processing circuit;

FIG. 20 is a partial enlarged view showing a step in yet anotherexemplary method of producing the body fluid processing circuit of theinvention;

FIG. 21 is a partial enlarged view showing the step subsequent to thestep shown in FIG. 20;

FIG. 22 is a partial enlarged view showing the step subsequent to thestep shown in FIG. 21;

FIG. 23 is a partial enlarged view showing a modification of the stepshown in FIG. 20;

FIG. 24 is a partial enlarged view showing a step in a further exemplarymethod of producing the body fluid processing circuit of the invention;

FIG. 25 is a partial enlarged view showing the step subsequent to thestep shown in FIG. 24;

FIG. 26 is a partial enlarged view showing the step subsequent to thestep shown in FIG. 25;

FIG. 27 is a partial enlarged view showing a step in another exemplarymethod of producing the body fluid processing circuit of the invention;

FIG. 28 is a partial enlarged view showing a modification of the stepshown in FIG. 27;

FIG. 29 is a partial enlarged view showing a modification of the stepshown in FIG. 27;

FIG. 30 is a partial enlarged view showing a step in a further exemplarymethod of producing the body fluid processing circuit of the invention;

FIG. 31 is a partial enlarged view showing the step subsequent to thestep shown in FIG. 30;

FIG. 32 is a partial enlarged view showing a step in another exemplarymethod of producing the body fluid processing circuit of the invention;

FIG. 33 is a partial enlarged view showing the step subsequent to thestep shown in FIG. 32;

FIG. 34 is a schematic diagram of the body fluid processing circuit ofthe invention;

FIG. 35 is a schematic diagram of the body fluid processing circuit inuse condition;

FIG. 36 is a schematic diagram of a prior art body fluid processingcircuit;

FIG. 37 is a partial enlarged view of the mixing/injecting portion inFIG. 36;

FIG. 38 is a schematic diagram illustrating how the mixing/injectingportion in FIG. 37 is assembled;

FIG. 39 is a partial enlarged view of FIG. 37;

FIG. 40 is a schematic diagram of the prior art body fluid processingcircuit in use condition; and

FIG. 41 shows an enlarged area around the branchline tube in the priorart body fluid processing circuit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present inventing will now be described in detail with particularreference to a body fluid processing circuit comprising a main tube madeof a synthetic resin and which has branchline tubes and processingportions such as a mixing/injecting portion welded at several sitesalong its length, as well as to a process for producing the circuit.

FIG. 1 is a schematic diagram illustrating an embodiment of theinvention for producing a body fluid processing circuit. Productionequipment 1A is constructed by an extrusion molding machine 1, a mold 2and an apparatus 3a for supplying a bottom member of a mixing/injectingportion. The mold 2 is fitted in the rear part with a line 5 forsupplying sterile air and a nozzle 5a associated with the sterile airsupply line 5 is provided to extend from the bottom of the mold 2. Inthe figure, numeral 10 is a suction pipe fitted with a tubular member 8at the front end thereof and connected to a suction pump 9 in the rearend thereof. The tubular member 8 is made of a synthetic resin.

Numeral 4 is a thermoplastic synthetic resin of which the main tube isto be formed; the resin in molten form is extruded from the moldingmachine 1 into the mold 2, from which it emerges through the nozzle 5ato form a tube.

Further referring to FIG. 1, a supplying apparatus 3a supplies andtransports the bottom member 13a for the mixing/injecting portion 13 (tobe described later and see FIG. 9) such that it is welded to a bottomsurface of the tube 4, which is an opposite surface to the side wherethe mixing/injecting portion 13 is to be provided. The suction pipe 10is driven back and forth (to the right and left in FIG. 1) and as shownin FIGS. 2 to 4, the bottom of the tubular member 8 is placed in contactwith the mounting surface of the tube 4 and its constituent material isaspirated so that the tubular member 8 is welded firmly to the tube 4,with a hole 11 being formed in the mounting surface of the tube 4.

The step of welding the bottom member 13a to the bottom surface of thetube 4 may be performed at any time after the end of extrusion of thetube 4 and as long as the tube 4 is maintained at elevated temperature.For example, the bottom member 13a may be welded to the tube 4simultaneously with the welding of the tubular member 8. Alternatively,the bottom member 13a may be welded to the tube 4 before or after thewelding of the tubular member 8.

In order to ensure positive welding to the tube 4, the bottom of thetubular member 8 and a groove 13b on the bottom member 13a of themixing/injecting portion 13 (at which the bottom member 13a contacts thebottom surface of the tube 4 which is opposite to its mounting surfacewhere the mixing/injecting portion 13 is to be provided) may be heatedbefore they are welded to the tube 4.

For example, the tubular member 8 may be supplied by a feed device 3c(having a hot plate 3d for transporting the tubular member 8 toward theextruded tube 4) such that the bottom of the tubular member 8 carried onthe hot plate 3d is heated with the hot plate 3d and maintained atelevated temperature while the top of the tubular member 8 is fitted onthe suction pipe 10 so as to weld the bottom of the tubular member 8 tothe mounting surface of the extruded tube 4 in the manner describedabove.

In addition, a heating device (not shown) may be provided above thebottom member 13a so that the groove 13b on the bottom member 13a isheated and maintained at elevated temperature while the bottom member13a is welded to the bottom surface of the extruded tube 4.

If desired, the feed apparatus 3a may be constructed by a hot plate sothat the groove 13b on the bottom member 13a is placed in contact withthe apparatus 3a and kept at elevated temperature while the bottommember 13a is welded to the bottom surface of the extruded tube 4.

The unit for heating the surfaces of the tubular member 8 and the bottommember 13a which are to be welded to the tube 4 is by no means limitedto those described above and any other techniques may be employed aslong as the intended result is attained.

The tube 4 is formed by using sterile air being supplied through thefeed line 5, so it can be maintained in an inflated state. Further, thetube 4 being extruded is kept in a closed system while the tubularmember 8 is fitted on the tube 4 and, hence, a clean operation can berealized in the absence of any dust and other foreign matter that mayotherwise be deposited in the interior of the tube 4.

FIG. 2 is an enlarged view showing the first step of welding the tubularmember 8 to the tube 4 being extruded from the mold 2. With the tubularmember 8 kept on groove 10b on its inner circumference by suction, thesuction pipe 10 is moved toward the mounting surface of the tube 4 andthe bottom of the tubular member 8 is brought into intimate contact withthe mounting surface of the tube 4 as shown in FIG. 3.

The constituent material of the tube 4 in areas around the bottom of thetubular member 8 is pulled toward the latter so that the tube 4 isfirmly welded to the tubular member 8. The constituent material of thetube 4 in contact with the bottom of the tubular member 8 further passesthrough the bore of the tubular member 8 so as to be sucked into thesuction pipe 10. As a result, a hole 11 is formed as shown in FIG. 4and, at the same time, the tubular member is welded to become anintegral part of the mounting surface of the tube 4. The outerperipheral surface of the hole 11 thus formed in the wall of the tube 11is slightly curved upward as shown in FIG. 4 and two primary factorsinvolved in this phenomenon are as follows: i) the suction provided bythe suction pipe 10 during the formation of the hole 11, and ii) thereaction to the movement of the tubular member 8 away from the tube 4 inorder to disconnect it from suction pipe 10 after the end of theaspiration.

If desired, aspiration may only be performed in the step of welding thebottom of the tubular member 8 to the mounting surface of the tube 4 andforming the hole 11. In this case, the tubular member 8 is not aspiratedas in FIG. 2 but is placed in light engagement with the groove 10b toprevent the tubular member from coming off; thereafter, suction isapplied to weld the bottom of the tubular member 8 the mounting surfaceof the tube 4 firmly and form the hole 11 in it; subsequently, thesuction is removed and the suction pipe 10 is moved away from the tube 4to be disengaged from the tubular member 8.

The tubular member 8 may be replaced by one of a different shape which,as indicated by 8a in FIG. 5, has a groove 8b formed on the innersurface. With suction being applied, the tip of the suction pipe 10 isplaced in engagement with the groove 8b and the procedure described byreference to FIGS. 2 to 4 is repeated to weld the tubular member 8a tobecome an integral part of the mounting surface of the tube 4 and formthe hole 11 as shown in FIGS. 5 to 7.

The tubular member 8a has the advantage that when the branchline tube 14is connected to the groove 8b as shown in FIG. 8, any steps that wouldotherwise form in the fluid passageway can be eliminated.

With respect to forming the mixing/injecting portion 13, a plug 22 suchas a rubber plug is pressed into the tubular member 8 and a cap 21 isfitted on its top as shown in FIG. 9 (section A--A of which is shown inFIG. 10). The outer peripheral surface of the hole 11 in the tube 4 isslightly curved toward the top of the tubular member 8 so that the lowerend of the plug 22 will not protrude from the lower edge of the hole 11.

The bottom member 13a fitted on the bottom surface of the tube 4 whichis remote form the tubular member 8 on the mounting surface of the tube4 has the advantage of ensuring safety during use since there is nopossibility for a needle piercing through the stopper 22 to penetratethe other side of the tube 4 to injure the operator.

In the embodiments described above, the tubular member 8 or 8a is weldedat right angles to the tube 4. In another embodiment of the invention, atubular member 8e may be welded at an angle to the tube 4 as shown inFIGS. 11 to 13. To do this, the tubular member 8e cut at an angle at thetip is placed in engagement with the groove 10b in the suction pipe 10under suction or, alternatively, the tubular member 8 is placed in lightengagement with the groove 10b in the absence of suction; subsequently,the suction pipe 10 is moved obliquely downward so that the bottom ofthe tubular member 8e contacts the mounting surface of the tube 4 andits constituent material is separated to have the bottom of the tubularmember 8e welded firmly to the tube 4 while forming a hole 11a in themounting surface of the tube 4 (see the sequence of steps shown in FIGS.11 to 13). Again, the outer peripheral surface of the hole 11a may becurved slightly upward as in the case of the hole 11.

FIG. 14 shows a modification of the method illustrated in FIGS. 11 to 13and a tubular member indicated by numeral 8f can also be welded to themounting surface of the tube 4, with a hole 11a being formed in it.

As in the case of the tubular member 8a, a branchline tube 14 can beconnected to the tubular member 8f. In addition, as in the case of thetubular member 8, a plug 22 may be pressed into the tubular member 8eshown in FIG. 13 with a cap 21 being fitted over the top to form amixing/injecting portion 13. In this case, a bottom member 13a may alsobe fitted on the bottom surface of the tube 4 which is an opposite sideto the tubular member 8e on the mounting surface of the tube 4.

The curvature and profile of the outer peripheral surface of the hole 11or 11a in the wall of the tube 4 can be freely adjusted by controllingvarious factors including the force of suction created by the suctionpipe 10, the timing at which the suction is removed after forming thehole 11 or 11a, and the speed at which the suction pipe 10 is moved awayfrom the tube 4. Preferably, the outer peripheral surface of the hole isslightly curved toward the mounting surface of the tube 4 as shown inFIG. 13. This is because the branchline tube 14 can be connected to thetubular member 8 without forming any steps in the fluid passageway (seeFIG. 8) and there is no obstacle to the passage of a fluid through thetube 4.

In the present invention, the bottom surface of the tubular member 8 (or8a, 8e or 8f) is welded to the tube 4 with suction being applied andthis ensures firm and consistent welding of the bottom surface of thetubular member 8 (or 8a, 8e or 8f) to the mounting surface of the tube 4without taking the trouble of providing a flange at the bottom of thetubular member. However, if desired, as shown in FIGS. 15 to 18, aflange 8d may be provided at the bottom of the tubular member (or 8a, 8eor 8f) to assist in the welding of the tubular member to the mountingsurface of the tube 4 so as to become an integral part of it whileforming a hole 11a or 11a in the surface.

FIG. 19 is a schematic diagram illustrating another embodiment of theinvention for producing a body fluid processing circuit. Numeral 6 is ajig having a suction port 7 (see FIG. 20) around which a tubular member8 is fitted and the rear end of which is connected to a suction pipe 10which, in turn, is connected to a suction pump 9. The jig 6 moves backand forth (to the right and left in FIG. 19) and, as shown in FIGS. 20to 22, the bottom of the tubular member 8 is welded to the tube 4 while,at the same time, the tip of the suction port 7 is placed in contactwith the mounting surface of the tube 4 (or pierced into or through themounting surface) so that the constituent material of that mountingsurface is aspirated, thereby permitting the tubular member 8 to befirmly welded to the tube 4 with a hole 11 being formed in its mountingsurface.

FIG. 20 is an enlarged view showing the first step of welding thetubular member 8 to the tube 4 being extruded from the mold 2. The jig 6around which the tubular member 8 is fitted and which has a flat tip ismoved toward the mounting surface of the tube 4 and, as shown in FIG.21, the tip of the jig 6 is placed in contact with the mounting surfaceof the tube 4 and, at the same time, the bottom surface of the tubularmember 8 is brought into intimate contact with the mounting surface.

When air is drawn through the suction port 7, the constituent materialof the tube 4 located around the tip of the suction port 7 is attractedtoward the tubular member 8, whereby the tubular member 8 is firmlywelded to the tube 4. Further, the constituent material of the tube 4which is in contact with the tip of the suction port 7 is drawn into thelatter, whereupon a hole 11 is formed and the tubular member 8 is weldedto the mounting surface of the tube 4 to become an integral part of it.The outer peripheral surface of the hole 11 in the tube 4 is curvedslightly upward under the action of two forces, one being the suctionthrough the suction port 7 and the other being the reaction to themovement of the suction port 7 away from the tube 4 after the suction isremoved following the formation of the hole 11 (see FIG. 22).

If desired, a tubular member 8a having an internal groove 8b may befitted around the jig 6 as shown in FIG. 23 and worked as in the processshown in FIGS. 20 to 22 so that the tubular member 8a is welded to themounting surface of the tube 4 to become an integral part of the latterwhile forming a hole 11 in the mounting surface.

In the foregoing description, the tubular member 8 (or 8a) fitted aroundthe jig 6 is welded at right angles to the tube 4. This is not alwaysthe case of the invention and as shown in FIGS. 24 to 26, a tubularmember 8e may be welded at an angle to the tube 4. For example, thetubular member 8e cut at an angle at the tip is fitted around the jig 6also cut at an angle at an end and the jig is driven obliquely downwardso that the bottom surface of the tubular member 8e is welded to thetube 4 and, at the same time, the tip of the suction port 7 is placed incontact with the mounting surface of the tube 4 and its constituentmaterial is aspirated to form the hole 11a in the mounting surface (seeFIGS. 24 to 26). Again, the outer peripheral surface of the hole 11a maybe curved slightly upward as in the case of the hole 11.

The profile of the outer peripheral surface of the hole 11 or 11a in thetube 4 can be adjusted freely by controlling various factors includingthe suction through the suction port 7, the depth to which the suctionport 7 is pierced into the mounting surface of the tube 4 (in case thatthe sharp-pointed suction port 7 may be pierced halfway the thickness ofthe wall or pierced through it completely), or the speed at which thesuction port 7 is moved away from the tube 4 after removing the suction.

In the embodiment just described above, the bottom surface of thetubular surface 8 (or 8a or 8e) is welded to the tube 4 with suctionbeing applied and this ensures firm welding of the bottom surface of thetubular member 8 (or 8a or 8e) to the mounting surface of the tube 4without taking the trouble of providing a flange at the bottom of thetubular member. However, if desired, as shown in FIGS. 27 to 29, aflange 8d may be provided at the bottom of the tubular member 8 (or 8aor 8e) to assist in the welding of the tubular member to the mountingsurface of the tube 4 to become an integral part of it while forming ahole 11 or 11a in the surface.

In the processes shown in FIGS. 20 to 22 and in FIGS. 24 to 26, the tipof the suction port 7 of the jig 6 is kept in contact with the mountingsurface of the tube 4 while its constituent material is aspirated toform the hole 11 or 11a. If desired, the suction port 7 of the jig 6 maybe cut to have a sharp-pointed end and pierced into the mounting surfaceof the tube 4 as shown in FIG. 30 or completely pierced through thesurface as shown in FIG. 32 and the constituent material of the tube 4is aspirated to form a hole which is indicated by 11b in FIG. 31 or 11cin FIG. 33. As already noted with reference to FIGS. 2 to 4, the outerperipheral surface of the hole 11b or 11c may be curved slightly upward.

After welding the tubular member 8 (or 8a, 8e or 8f) to the mountingsurface of the tube 4 and forming the hole 11 or 11a in it, thebranchline 14 is connected to the tubular member and/or the plug 22 ispressed into the tubular member and given the necessary work toconstruct the mixing/injecting portion (processing portion) 13 and thetube 4 is cut to a specified length; thereafter, a rolling tube 41, adrip chamber 42, a shunt adapter 43 and any other components of amedical device such as a container in bag form or a needle areconnected-to the tube to assemble a body fluid processing circuit (amedical device having branches). Alternatively, the body fluidprocessing circuit (the medical device having branches) is firstassembled by connecting the necessary components of the medical deviceand thereafter the branchline tube 14 is connected to the tubular member8 (or 8a, 8e or 8f) and further the mixing/injecting portion (processingportion) 13 may be constructed.

As described on the foregoing pages, the jig 6 may be fitted on top ofthe tubular member 8 (or 8a, 8e or 8f) so that its bottom is welded tothe mounting surface of the tube 4 to become an integral part of thelatter; alternatively, the jig 6 is dispensed with and the suction pipe10 is directly connected to the top of the tubular member 8 (or 8a, 8eor 8f) and suction is applied to ensure that the bottom of the tubularmember is firmly welded to the mounting surface of the tube 4; in eithercase, the hole 11 (or 11a, 11b or 11c) can be formed in the mountingsurface of the tube 4 so that the interior of the tubular member 8 (or8a, 8e or 8f) communicates with the interior of the tube 4.

The concept of the invention is applicable not only to the body fluidprocessing circuit described above in detail but also to all kinds ofmedical devices having branches that are mentioned in the Background ofthe Invention, as exemplified by body fluid processing circuits,administration, blood sampling-and blood transfusion bags which are tobe used either alone or in connection to those sets and circuits. Hence,it should be understood that the scope of the invention encompasses allkinds of medical devices having branches.

In the invention, the main tube 4 and the tubular member 8 (or 8a, 8e or8f) may assume any cross-sectional shape such as a circle, ellipsis,square or a rectangle. If the tube 4 in a circular or elliptical form isto be welded to the tubular member which is also circular or elliptical,the welding operation may be facilitated by forming a groove in thebottom of the tubular member 8 (8a, 8e or 8f) or the flange 8d which iscurved inward as in the case of the groove 13b in the bottom member 13asuch that it conforms to the curvature of the mounting surface of thetube 4.

The body fluid processing circuit of the invention has the followingadvantages.

(1) Since the outer peripheral surface of the hole formed in themounting surface of the main tube is curved upward (i.e., toward themounting surface), blood can maintain a laminar flow through the maintube without forming any residue or experiencing any other troubles thatfrequently occur in the prior art due to blockage.

(2) The hole mentioned in (1) can be formed both at the site ofconnection to a branchline tube and at the site of formation of amixing/injecting portion by the same method at the same time and in apositive manner.

(3) The bottom surface of the tubular member is welded to the tube withsuction being applied and this ensures the bottom surface of the tubularmember to be firmly welded to the mounting surface of the tube.

(4) Because of (3), although the body fluid processing circuit can bebent in areas near the tubular member during use, as shown in FIG. 35,the kink are less likely to develop in the main tube and, hence, anefficient operation is achieved.

(5) The main tube need not be cut to provide branches and this leads toa marked improvement in process efficiency.

(6) In the absence of seams along the length of the main tube, theproblems that frequently occur in the related art such as bloodcoagulation, residual blood and hemolysis are eliminated are solved, andeven if the addition of heparin to blood is reduced, it can bemaintained in a state very close to the blood circulation in the humanbody.

(7) The hole to be formed in the mounting surface of the main tube canbe reduced in diameter by a sufficient amount to eliminate the chance ofblood coagulation, residual blood, homolysis and other troubles to occurin areas around the hole.

(8) Those portions which correspond to the interior of the body fluidprocessing circuit from the ambient atmosphere throughout the process ofits manufacture starting with the extrusion of respective components andending with the construction of a final assembly and, hence, completeaseptic and dust-free manufacture of the body fluid processing circuitcan be realized.

(9) Since the heated tubular member is welded to the main tube beingextruded at a comparably high temperature, the former can be mountedeasily on the latter and yet firm fixing can be accomplished.

(10) Since no solvents are used, the solvent problem frequentlyencountered in the related art due to solvent dissolution in the bloodand subsequent potential circulation in the human body can be totallyeliminated to secure high hygiene and safety features.

What is claimed is:
 1. A medical device having branches, whichcomprises:a first tube formed in a straight form, said first tube beingseamless along its length; and a second tube welded firmly to a mountingsurface of said first tube; wherein a hole is formed in said first tubeso as to communicate with said second tube; and the outer peripheralsurface of said hole is curved toward the mounting surface of said firsttube.
 2. The medical device according to claim 1, which further includesat least one of a branchline tube connected to a top of said second tubeand a plug pressed into said second tube, to thereby form a processingportion.
 3. The medical device according to claim 1, which furtherincludes a bottom member mounted on an opposite side of said first tubeto said second tube provided on said mounting surface of said firsttube.
 4. The medical device according to claim 1, wherein said secondtube is welded at right angles to said first tube.
 5. The medical deviceaccording to claim 1, wherein said second tub is welded at an angle tosaid first tube.
 6. The medical device according to claim 2, whereinsaid second tube has a groove to which said branchline tube is connectedwithout steps between said second tube and said branchline tube.